I delete someones number but after an hour it appear again on my phonebook

[bechay]

I delete someones number but after an hour it appear again on my viber whatsapp and my phonebook

 

[Titillating]

Are your various apps set to auto-sync? If you only deleted them on one app, their information is probably still in the other apps. If they're also set to auto-sync, your phone will pull that information and add it back into your contacts.